1. Field of the Invention
This invention relates to a blow bar for an impact crusher, in particular a rotary impact crusher, having a carrier, which, in a region of a cutting edge, has a plurality of cutting elements made of hard material arranged next to one another.
2. Discussion of Related Art
European Patent Reference EP 0 581 758 B1 discloses a rotary impact crusher equipped with several blow bars. The blow bar includes a carrier that can be clamped by a wedge clamp to an anchoring attachment to permit the blow bar to be interchangeably affixed to the rotor of a rotary impact crusher. The carrier has a seating surface facing in the tool-advancing direction onto which a plurality of cutting elements are placed and can be lined up in a longitudinal direction of the blow bar. The cutting elements are first placed loosely onto the carrier. As soon as the wedge connection is clamped, then the cutting elements are affixed to the carrier in captive fashion. If one or more of the cutting elements becomes worn, then the clamped connection must be released. Then the respective cutting elements can be replaced with non-worn cutting elements. This known type of fixing the cutting elements to the carrier has turned out to be unsuitable in actual practice. In particular, when the blow bar to be serviced is in a lower position of the rotor, after the clamped connection is released, the cutting elements can fall in an uncontrolled fashion and must then be laboriously collected and placed onto the carrier. Furthermore, the contact surfaces of the carrier and cutting elements must be very precisely matched to one another in order to enable a gap-free connection. Because the cutting elements, which are embodied as sintered components, can only be produced within a certain tolerance range, the gap-free association with the carrier can never be completely guaranteed, leading to frequent breakage of cutting elements.
German Patent Reference DE 23 43 691 discloses another blow bar having three hard metal plates fastened to a carrier. Here, a screw connection is used to clamp the hard metal plates into recesses in the carrier. German Patent Reference DE 295 21 050 U1 discloses a similar arrangement in which the carrier of the blow bar has a dovetail-shaped groove into which a dovetail-shaped insertion lug of the bar-shaped cutting element is slid. In blow bars of this type, there is frequently the danger that powerful impact stress results in bar breakage. Then, the entire cutting element must be expensively replaced.
German Patent Reference DE 16 58 400 U1 discloses another blow bar in which a hard metal block extending the entire width of the blow bar is soldered to the carrier.